This document provides an introduction to use of the Web by people with disabilities. It illustrates some of their requirements when using Web sites and Web-based applications, and provides supporting information for the guidelines and technical work of the World Wide Web Consortium's (W3C) Web Accessibility Initiative (WAI).

Please do not link to, reference, or quote this draft because it is currently an unapproved internal draft and some of the techniques and terminology are out-of-date; for example, WCAG 2.0 is now recommended instead of WCAG 1.0. After it is completed, we will grant additional permission to use this material with appropriate reference.

The Web Accessibility Initiative (WAI) develops guidelines for accessibility of Web sites, browsers, and authoring tools, in order to make it easier for people with disabilities to use the Web. Given the Web's increasingly important role in society, access to the Web is vital for people with disabilities. Many of the accessibility solutions described in WAI materials also benefit Web users who do not have disabilities.

NB. Links for WAI guidelines in following paragraph are changed to link to the Introductory pages for each guideline rather than the Guidelines themselves

scenarios of people with disabilities using accessibility features of Web sites and Web-based applications;

general requirements for Web access by people with physical, visual, hearing, and cognitive or neurological disabilities;

some types of assistive technologies and adaptive strategies used by some people with disabilities when accessing the Web.

This document contains many internal hypertext links between the sections on scenarios, disability requirements, assistive technologies,
and scenario references. The scenario references and general references sections also include links to external documents.

The following scenarios show people with different kinds of disabilities using assistive technologies and adaptive strategies to access the Web. In some cases the scenarios show how the Web can make some tasks easier for people with disabilities.

Please note that the scenarios do not represent actual individuals, but rather individuals engaging in activities that are possible using today's Web technologies and assistive technologies. The reader should not assume that everyone with a similar disability to those portrayed will use the same assistive technologies or have the
same level of expertise in using those technologies. In some cases, browsers, media players, or assistive technologies with specific
features supporting accessibility may not yet be available in an individual's primary language. Disability terminology varies from one country to another, as do educational and employment opportunities.

Each scenario contains links to additional information on the specific disability or disabilities described in more detail in Section
3; to the assistive technology or adaptive strategy described in Section 4; and to detailed curriculum examples or guideline checkpoints in the Scenarios
References in Section 6. NB links added to sections 3, 4 & 6.

Mr. Lee wants to buy some new clothes, appliances, and music. As he frequently does, he is spending an evening
shopping online. He has one of the most common visual disabilities for men: color blindness, which in his case
means an inability to distinguish between green and red.

He has difficulty reading the text on many Web sites. When he first {starting}[started] using the Web, it seemed to him the text and images on a lot of sites used poor color contrast, since they appeared to use similar shades of brown. He realized that many sites were using colors that
were indistinguishable to him because of his red/green color blindness. In some cases the site instructions explained that discounted prices were indicated by red text, but all of the text looked brown to him. In other cases, the required fields on forms were indicated by red text, but again he could not tell which fields had red text.

Mr. Lee found that he prefered sites that used sufficient color contrast, and redundant information for color. The sites did this by including names of the colors of clothing as well as showing a sample of the color; [adding an asterisk to discounted prices in addition to showing them in red;] and by {placing an asterix (*) in front of}[clearly indicating] the required fields [on the order form] in addition to {indicated}[indicating] them by color.

Mr. Jones is a reporter who must submit his articles in HTML for publishing in an on-line journal. Over his twenty-year career, he has developed repetitive stress injury (RSI) in his hands and arms, and it has become painful for him to type. He uses a combination of speech recognition and an alternative keyboard to prepare his articles, but he doesn't use a mouse. It [initially] took him several months to become sufficiently accustomed to using speech recognition to be comfortable working for many hours at a time [, however the software he recently acquired took far less effort to train to his voice]. There are some things he has not worked out yet, such as a sound card conflict that arises whenever he tries to use speech recognition on Web sites that have streaming audio. @@ is this conflict still an issue?

He has not been able to use the same Web authoring software as his colleagues, because the application that his office chose for a standard is missing many of the keyboard equivalents that he needs in place of mouse-driven commands. To activate commands that do not have keyboard equivalents, he would have to use a mouse instead of speech recognition or typing, and this would re-damage his hands at this time. He researched some of the newer versions of authoring tools and selected one with full keyboard support. Within a month, he discovered that several of his colleagues have switched to the new product as well, after they found that the full keyboard support was easier on their own hands. [Mr Jones' company also maintains several thematic blogs that staff are expected to contribute to - Mr Jones helped them select blogging software that provided keyboard support in the Web application, including short-cut keys for common actions.]

{When browsing other Web sites to research some of his articles, Mr. Jones likes the access key feature that is implemented on some Web pages. It enables him to shortcut a long list of links that he would ordinarily have to tab through by voice, and instead go straight to the link he wants.}

[When Mr Jones browses the Web to research some of his articles, he uses a browser that supports keyboard navigation by headings as well as by links as this allows him to quickly get to the section of the page that is of interest on those pages that use proper headings. He also appreciates sites that have incorporated a means to skip over the common navigation and get straight to the main material on the page. ]
@@ possible scenario references - 'skip to content', 'proper headings', keyboard navigation'

@@ NB change access keys example above to:
a) web applications that can be used with the keyboard OR
b) heading navigation (as provided by Opera)

Ms. Martinez is taking several distance learning courses in physics. She is deaf. She had little trouble with the curriculum until the university upgraded their on-line courseware to a multimedia approach, using an extensive collection of audio lectures. For classroom-based lectures the university provided interpreters; however for Web-based instruction they initially did not realize that accessibility was an issue, then said they had no idea how to provide the material in accessible format. She was able to point out that the University was clearly covered by a policy requiring accessibility of online instructional material, and then to point to the Web Content Accessibility Guidelines{1.0} as a resource providing guidance on how to make Web sites, including those with multimedia, accessible.

The University had the lectures transcribed and made this information available through their Web site along with audio versions of the lectures. For an introductory multimedia piece, the University used a SMIL-based multimedia format enabling synchronized captioning of audio and description of video. The school's information managers quickly found that it was much easier to comprehensively index the audio resources on the accessible area of the Web site, once these resources were captioned with text. [They also found they could provide captions in other languages to attract international students.]

The professor for the course also set up a [text] chat area on the Web site where students could exchange ideas about their coursework. Although she was the only deaf student in the class and only one other student knew any sign language, she quickly found that the Web-based chat format, and the opportunity to provide Web-based text comments on classmates' work, ensured that she could keep up with class progress. [As Ms Martinez's family have broadband at home, she uses video chat to sign to with her family as well as using text-based chat.]

@@ mention need for online media player supporting captions?
@@ consider adding a note about the advantage of multimedia with captions which can be used to translate the multimedia
@@ video chat for signing with family via broadband connection

Ms. Laitinen is an accountant at an insurance company that uses Web-based formats over a corporate intranet. She is blind. She uses a screen reader to interpret what is displayed on the screen and generate a combination of speech output and refreshable braille output. She uses the speech output, combined with [keyboard navigation by headings and links,]{tabbing through the navigation links on a page,} for rapid scanning of a document, and has become accustomed to listening to speech output at a speed that her co-workers cannot understand at all. She uses refreshable braille output to check the exact wording of text [and confirm numeric data], since braille enables her to read the [content of]{language on} a page more precisely.

Much of the information on the Web documents used at her company [is numbers] in tables, which can sometimes be difficult for non-visual users to read. However, since the tables on this company's documents are marked up clearly with column and row headers[and orientation summaries are provided] which her screen reader can access, she easily orients herself to the information in the tables. Her screen reader reads her the alternative text for any images on the site. Since the insurance codes she must frequently reference include a number of abbreviations and acronyms, she finds the expansions of abbreviations and acronyms the first time they appear on a page allows her to better catch the meaning of the short versions of these terms.

Ms. Olsen attends middle school, and particularly likes her literature class. She has attention deficit disorder with dyslexia, and the combination leads to substantial difficulty reading. However with recent accommodations to the curriculum she has become enthusiastic about this class.

Her school recently started to use more online curricula to supplement class textbooks. She was initially worried about [the] reading load, since she reads slowly. But recently she tried text to speech software, and found that she was able to read along visually with the text much more easily when she could hear certain sections of it read to her with the speech synthesis, instead of struggling over every word.

Her classes recent area of focus is Hans Christian Andersen's writings, and she has to do some research about the author. When she goes onto the Web, she finds that some sites are much easier for her to use than others. Some of the pages have a lot of graphics, and those help her focus in quickly on sections she wants to read. In some cases, though, where the graphics are animated, it is very hard for her to focus, and so it helps to be able to freeze the animated graphics.

One of the most important things for her has been the level of accessibility of the Web-based online library catalogues and the general search functions on the Web. Sometimes the search options are confusing for her. Her teacher has taught a number of different search strategies, and she finds that [some sites provide error corrections and suggest alternative spellings, which assists her significantly.]{some sites provide options for a variety of searching strategies and she can more easily select searching options that work well for her.}

He uses [browser-based zooming]{a screen magnifier} to help with his vision and his hand tremor; when the [links and form elements]{icons and links} on Web pages are bigger, it's easier for him to select them, and so he finds it easier to use pages with style sheets. When he first started using some of the financial pages, he found the scrolling stocktickers distracting, and they moved too fast for him to read. In addition, sometimes the pages would update before he had finished reading them. Therefore he tends to use Web sites that do not have a lot of movement in the text, and that do not auto-refresh. He also tended to "get stuck" on some pages, finding that he could not back up, on some sites where new browser windows would pop open without notifying him.

Mr. Yunus has gradually found some sites that work well for him, and developed a customized profile at some banking, grocery, and clothing sites [and that don't time him out part-way through his transactions without warning].

@@ TF suggestion - screen magnifiers are not widely used among older people. Maybe change that to resizable text without overlapping, cropping of text (or use in another scenario) [@@ what about horizontal scrolling issue?]
@@ link to 'Timing Adjustable' in Scenario refs

Civil engineer with arthritis and central vision loss

Mr Smith is nearing retirement age as a Senior Engineer with a large civil engineering firm. He has recently been put in charge of training and assessment for engineering staff and is responsible for maintaining part of professional development information on the firm's intranet. His firm has implemented a Web-based authoring tool that allows for full keyboard support which Mr Smith appreciates as his arthritis makes mouse use difficult, especially clicking and drag & drop actions. He also uses the Web to keep abreast of professional developments via engineering forums and online Journals. In adition to arthritis, Mr Smith is aslo experiencing early age related macular degeneration (AMD) affecting his central vision, resulting in a need to increase text size on the screen.

Mr Smith uses a Web browser that allows him to navigate by headings and links around a Web page using the keyboard, though he finds some pages have text that looks like headings and links but that can't be used for navigation. He also finds on some Web pages that the text starts to overlap if he increases the text size too much, which he is finding an increased need to do as many sites seem to have very small text. He still perseveres with the mouse on pages where there are too many links to navigate efficiently by keyboard, but finds the radio buttons in forms and clicking small links challenging.

After work, Mr Smith is also a keen fisherman and participates in several online fishing forums that he has found that can be used without a mouse, just the keyboard. Facing compulsory retirement shortly due to his age he finds people keep telling him "now you'll get to fish all
the time" but he knows he would tire of that quickly and miss the engineering side of his life. Besides, the arthritis is making it difficult to handle the fishing tackle. He would prefer to keep working part-time, and could easily undertake many of his tasks from home. He already maintains the web pages for the local fishing club, but that is not challenging enough.

Grandmother with age-related impairments

Mrs Jones is an (@@ 85 year old) great-grandmother with children and grandchildren she likes to keep in touch with. Her daughter helped her buy a notebook computer a couple of years ago and she got started by attending a class at the local senior citizen's' center. She also relies on her daughter and granddaughter to help her when she has any difficulty with programs. She uses web-based email for communicating with her far-flung family and has recently been shown some social-networking and photo sharing sites and signed up to them. She loves all the information she can find on the web through the search engines, though it is often overwhelming in its quantity. She particularly likes looking for health information and researching her travel online before going to talk to the travel agent, though she finds the continual movement on some sites rather distracting. She also watches missed episodes of her favorite television programs on the TV channel websites.

Like many of her friends, Mrs Jones is experiencing several age-related impairments including severe hearing loss, reduced vision and associated glare sensitivity along with mild cognitive impairment that makes her forgetful and easily distracted. To counter some of these impairments her granddaughter has changed her mouse pointer to a larger size, set her browser default background color to off-white and increased the default font size (and written down the instructions for page zooming as sometimes she needs more magnification). She also found out about video subtitles [@@ captioning] from the senior citizen's center during a special training day and appreciates the subtitling available with many of them of the online program replays from the TV stations, but wishes everyone would do it.

Semi-retiree with tremors

volunteers at local charity - setting up promotional information website for them

experiences essential tremor - becoming more severe over the last decade

also experiences lower vision (accuity and contrast impacts) and hard of hearing

@@ needs expansion

maybe add into Mr Yunus?

Older female person, blind since her youth, accessing bank accounts

Ms Schmidt is an older women who has been blind since childhood and uses a computer with the help of screen reader software and a refreshable Braille device. She jumped at the chance to work with computers and assistive technologies at the first opportunity as it greatly increased her communications and access options. One of the most important tasks she undertakes on the Web is managing her bank accounts. In her younger days she always had to take a trusted friend along to the bank to fill in the forms for her. Initially internet banking's security had precluded her from banking online, however much negotiation with the support of the national blindness organisation resulted in secure login procedures that she could use. In adition to a regular CAPTCHA there is also an audio CAPTCHA and a mobile phone text message option. As Ms Schmidt is experiencing some age related hearing loss, she now opts for the text-message option as she finds the audio messages hard to discern from the intentional background sound.

In addition to providing accessible secure login options, Ms Smchidt's bank has implemented other accessibility features including labels for form elements and buttons ensuring that helpful information about the success or failure of every transaction is clearly indicated and always placed always at the same position at the start of the page, and providing logout warnings and options to extend the timeouts.

Mr. Sands has put groceries in bags for customers for the past year at a supermarket. He has Down syndrome, and has difficulty with abstract concepts, reading, and doing mathematical calculations. He usually buys his own groceries at this supermarket, but sometimes finds that there are so many product choices that he becomes confused, and he finds it difficult to keep track of how much he is spending. He has difficulty re-learning where his favorite products are each time the supermarket changes the layout of its products.

Recently, he visited an online grocery service from his computer at home. He explored the site the first few times with a friend. He found that he could use the Web site without much difficulty -- it had a lot of pictures, which were helpful in navigating around the site, and in recognizing his favorite brands.

His friend showed him different search options that were available on the site, making it easier for him to find items. He can search by brand name or by pictures, but he mostly uses the option that lets him select from a list of products that he has ordered in the past. Once he decides what he wants to buy, he selects the item and puts it into his virtual shopping basket. The Web site gives him an updated total each time he adds an item, helping him make sure that he does not overspend his budget.

The marketing department of the online grocery wanted their Web site to have a high degree of usability in order to be competitive with other online stores. They used consistent design and consistent navigation options so that their customers could learn and remember their way around the Web site. They also used the clearest and simplest language appropriate for the site's content so that their customers could quickly understand the material.

While these features made the site more usable for all of the online-grocery's customers, they made it possible for Mr. Sands to use the site. Mr. Sands now shops on the online grocery site a few times a month, and just buys a few fresh items each day at the supermarket where he works.

@@ TF note - why is it emphasized here that the site was more usable? that is also true for other scenarios - maybe this could be drawn out at the start and/or end of the scenarios [possible cross reference to accessibility-usability relationship]

At home, Ms. Kaseem browses local Web sites for new and different restaurants. She uses a personal style sheet with her browser, which makes all Web pages display according to her preferences. Her preferences include having background patterns turned off so that there is enough contrast for her when she uses screen magnification. This is especially helpful when she reads on-line sample menus of appealing restaurants.

A multimedia virtual tour of local entertainment options was recently added to the Web site of the city in which Ms. Kaseem lives. The tour is captioned and described -- including text subtitles for the audio, and descriptions of the video -- which allows her to access it using a combination of screen magnification and braille. The interface used for the virtual tour is accessible no matter what kind of assistive technology she is using -- screen magnification, her screen reader with refreshable braille, or her portable braille device. Ms. Kaseem forwards the Web site address to friends and asks if they are interested in going with her to some of the restaurants featured on the tour.

She also checks the public transportation sites to find local train or bus stops near the restaurants. The Web site for the bus schedule has frames without meaningful titles, and tables without clear column or row headers, so she often gets lost on the site when trying to find the information she needs. The Web site for the local train schedule, however, is easy to use because the frames on that Web site have meaningful titles, and the schedules, which are laid out as long tables with clear row and column headers that she uses to orient herself even when she has magnified the screen display.

Occasionally she also uses her portable braille device, with an infrared connection, to get additional information and directions at a publicly-available information kiosk in a shopping mall downtown; and a few times she has downloaded sample menus into her braille device so that she has them in an accessible format once she is in the restaurant.

This section describes general kinds of disabilities that can affect access to the Web. There are as yet no universally accepted categorizations of disability, despite efforts towards that goal. Commonly used disability terminology varies from country to country and between different disability communities in the same country. There is a trend in many disability communities to use functional terminology instead of medical classifications. This document does not attempt to comprehensively address issues of terminology.

Abilities can vary from person to person, and over time, for different people with the same type of disability. People can have combinations of different disabilities, and combinations of varying levels of severity.

The term "disability" is used very generally in this document. Some people with conditions described below would not consider themselves to have disabilities. They may, however, have limitations of sensory, physical or cognitive functioning which can affect access to the Web. These may include injury-related and aging-related conditions, and can be temporary or chronic.

The number and severity of limitations tend to increase as people age, and may include changes in vision, hearing, memory, or motor function. Aging-related conditions can be accommodated on the Web by the same accessibility solutions used to accommodate people with disabilities.

Sometimes different disabilities require similar accommodations. For instance, someone who is blind and someone who cannot use his or her hands both require full keyboard equivalents for mouse commands in browsers and authoring tools, since they both have difficulty using a mouse but can use assistive technologies to activate commands supported by a standard keyboard interface.

Many accessibility solutions described in this document contribute to "universal design" (also called "design for all") by benefiting non-disabled users as well as people with disabilities. For example, support for speech output not only benefits blind users, but also Web users whose eyes are busy with other tasks; while captions for audio not only benefit deaf users, but also increase the efficiency of indexing and searching for audio content on Web sites.

Each description of a general type of disability includes several brief examples of the kinds of barriers someone with that disability might encounter on the Web. These lists of barriers are illustrative and not intended to be comprehensive. Barrier examples listed here are representative of accessibility issues that are relatively easy to address with existing accessibility solutions, except where otherwise noted.

Following is a list of some disabilities and their relation to accessibility issues on the Web.

There are many types of low vision (also known as "partially sighted" in parts of Europe), for instance poor acuity (vision that is not sharp), tunnel vision (seeing only the middle of the visual field), central field loss (seeing only the edges of the visual field), and clouded vision. [Low vision can be experienced at any time of life, but is particularly prevalent amongst older people who also commonly experience reduced contrast sensitivity.]

To use the Web, some people with low vision use extra-large monitors, and increase the size of system fonts and images. Others use screen magnifiers or screen enhancement software. Some individuals use specific combinations of text and background colors, such as a 24-point bright yellow font on a black background, or choose certain typefaces that are especially legible for their particular vision requirements.

Barriers that people with low vision may encounter on the Web can include:

Web pages with absolute font sizes that do not change (enlarge or reduce) easily

Web pages that, because of inconsistent layout, are difficult to navigate when enlarged, due to loss of surrounding context

Web pages, or images on Web pages, that have poor contrast, and whose contrast cannot be easily changed through user override of author style sheets

Text presented as images, which prevents wrapping to the next line when enlarged, [and becomes blured when enlarged]

also many of the barriers listed for blindness, above, depending on the type and extent of visual limitation

[overlap of graphics & text or text & text when browser is used to enlarge the page]

Color blindness is a lack of sensitivity to certain colors. Common forms of color blindness include difficulty distinguishing between red and green, or between yellow and blue. Sometimes color blindness results in the inability to perceive any color.

To use the Web, some people with color blindness use their own style sheets to override the font and background color choices of the author.
@@ add emphasis about Browsers that make it difficult to change style sheets

Barriers that people with color blindness may encounter on the Web can include:

color that is used as a unique marker to emphasize text on a Web site

text that inadequately contrasts with background color or patterns

browsers that do not support user override of authors' style sheets

[browsers that hide/bury the ability to customize the users experience]

Hearing Impairments

Deafness involves a substantial uncorrectable impairment of hearing in both ears. Some deaf individuals' first language is a sign language, and they may or may not read a written language fluently, or speak clearly.

To use the Web, many people who are deaf rely on captions for audio content. They may need to turn on the captions on an audio file as they browse a page; concentrate harder to read what is on a page; or rely on supplemental images to highlight context.

Barriers that people who are deaf may encounter on the Web can include:

lack of captions or transcripts of audio on the Web, including webcasts

lack of content-related images in pages full of text, which can slow comprehension for people whose first language may be a sign language instead of a written/spoken language

A person with a mild to moderate hearing impairment may be considered hard of hearing.

To use the Web, people who are hard of hearing may rely on captions for audio content and/or amplification of audio. They may need to toggle the captions on an audio file on or off, or adjust the volume of an audio file.

Barriers encountered on the Web can include:

lack of captions or transcripts for audio on the Web, including webcasts

[foreground/background audio contrast

@@ overall audio volume?]

Physical disabilities

Motor disabilities can include weakness, limitations of muscular control (such as involuntary movements [including tremors], lack of coordination, or paralysis), limitations of sensation, joint problems [(such as arthritis)], or missing limbs. Some physical disabilities can include pain that impedes movement. These conditions can affect the hands and arms as well as other parts of the body.

To use the Web, people with motor disabilities affecting the hands or arms may use a specialized mouse [or track ball]; a keyboard with a layout of keys that matches their range of hand motion; a pointing device such as a head-mouse, head-pointer or mouth-stick; voice-recognition software; an eye-gaze system; or other assistive technologies to access and interact with the information on Web sites. They may activate commands by typing single keystrokes in sequence with a head pointer rather than typing simultaneous keystrokes ("chording") to activate commands. They may need more time when filling out interactive forms on Web sites if they have to concentrate or maneuver carefully to select each keystroke.

Barriers that people with motor disabilities affecting the hands or arms may encounter include:

time-limited response options on Web pages

browsers and authoring tools that do not support keyboard alternatives for mouse commands

forms that cannot be tabbed through in a logical order

[forms that don't have the labels linked to the control

pages with scripted components that can only be accessed by mouse clicks

@@ complex pages without in-page navigation to quickly get to the relevant section]

Cognitive and neurological disabilities

Individuals with visual and auditory perceptual disabilities, including dyslexia (sometimes called "learning disabilities" in Australia, Canada, the U.S., and some other countries) and dyscalculia may have difficulty processing language or numbers. They may have difficulty processing spoken language when heard ("auditory perceptual disabilities"). They may also have difficulty with spatial orientation.

To use the Web, people with visual and auditory perceptual disabilities may rely on getting information through several modalities at the same time. For instance, someone who has difficulty reading may use a screen reader plus synthesized speech to facilitate comprehension, while someone with an auditory processing disability may use captions to help understand an audio track.

Barriers that people with visual and auditory perceptual disabilities may encounter on the Web can include:

lack of alternative modalities for information on Web sites, for instance lack of alternative text that can be converted to audio to supplement visuals, or the lack of captions for audio

Individuals with impairments of intelligence (sometimes called "learning disabilities" in Europe; or "developmental disabilities" or previously "mental retardation" in the United States) may learn more slowly, or have difficulty understanding complex concepts. Down Syndrome is one among many different causes of intellectual disabilities.

To use the Web, people with intellectual disabilities may take more time on a Web site, may rely more on graphics to enhance understanding of a site, and may benefit from the level of language on a site not being unnecessarily complex for the site's intended purpose.

Some individuals with seizure disorders, including people with some types of epilepsy (including photo-sensitive epilepsy), are triggered by visual flickering or audio signals at a certain frequency.

To use the Web, people with seizure disorders may need to turn off animations, blinking text, or certain frequencies of audio. Avoidance of these visual or audio frequencies in Web sites helps prevent triggering of seizures.

Combinations of disabilities may reduce a user's flexibility in using accessibility information.

For instance, while someone who is blind can benefit from hearing an audio description of a Web-based video, and someone who is deaf can benefit from seeing the captions accompanying audio, someone who is both deaf and blind needs access to a text transcript of the description of the audio and video, which they could access on a refreshable braille display.

Similarly, someone who is deaf and has low vision might benefit from the captions on audio files, but only if the captions could be enlarged and the color contrast adjusted.

Someone who cannot move his or her hands, and also cannot see the screen well, might use a combination of speech input and speech output, and might therefore need to rely on precise indicators of location and navigation options in a document.

Changes in people's functional ability due to aging can include changes in abilities or a combination of abilities including vision, hearing, dexterity and memory. Barriers can include any of the issues already mentioned above. Any one of these limitations can affect an individual's ability to access Web content. Together, these changes can become more complex to accommodate.

For example, someone with low vision may need screen magnification, however when using screen magnification the user loses surrounding contextual information, which adds to the difficulty which a user with short-term memory loss might experience on a Web site.

@@ discuss range of impairments more comprehensively as per slides
@@ not static, but often an evolving situation

Assistive technologies are products used by people with disabilities to help accomplish tasks that they cannot accomplish otherwise or could not do easily otherwise. When used with computers, assistive technologies are sometimes referred to as adaptive software or hardware.

Some assistive technologies are used together with graphical desktop browsers, text browsers, voice browsers, multimedia players, or plug-ins. Some accessibility solutions are built into the operating system, for instance the ability to change the system font size, or configure the operating system so that multiple-keystroke commands can be entered with a sequence of single keystrokes.

Adaptive strategies are techniques that people with disabilities use to assist in using computers or other devices. For example someone who cannot see a Web page may tab through the links on a page as one strategy for helpinjg skim the content.

Following is a list of the assistive technologies and adaptive strategies described below. This is by no means a comprehensive list of all such technologies or strategies, but rather explanations of examples highlighted in the scenarios above.

Alternate keyboards or switches are hardware or software devices used by people with physical disabilities, that provide an alternate way of creating keystrokes that appear to come from the standard keyboard. Examples include keyboard with extra-small or extra-large key spacing, keyguards that only allow pressing one key at a time, on-screen keyboards, eyegaze keyboards, and sip-and-puff switches. Web-based applications that can be operated entirely from the keyboard, with no mouse required, support a wide range of alternative modes of input.

Braille is a system using six to eight raised dots in various patterns to represent letters and numbers that can be read by the fingertips. Braille systems vary greatly around the world. Some "grades" of braille include additional codes beyond standard alpha-numeric characters to represent common letter groupings (e.g., "th," "ble" in Grade II American English braille) in order to make braille more compact. An 8-dot version of braille has been developed to allow all ASCII characters to be represented. Refreshable or dynamic braille involves the use of a mechanical display where dots (pins) can be raised and lowered dynamically to allow any braille characters to be displayed. Refreshable braille displays can be incorporated into portable braille devices with the capabilities of small computers, which can also be used as interfaces to devices such as information kiosks.

Scanning software is adaptive software used by individuals with some physical or cognitive disabilities that highlights or announces selection choices (e.g., menu items, links, phrases) one at a time. A user selects a desired item by hitting a switch when the desired item is highlighted or announced.

Screen magnification is software used primarily by individuals with low vision that magnifies a portion of the screen for easier viewing. At the same time screen magnifiers make presentations larger, they also reduce the area of the document that may be viewed, removing surrounding context . Some screen magnifiers offer two views of the screen: one magnified and one default size for navigation.

Software used by individuals who are blind or who have dyslexia that interprets what is displayed on a screen and directs it either to speech synthesis for audio output, or to refreshable braille for tactile output. Some screen readers use the document tree (i.e., the parsed document code) as their input. Older screen readers make use of the rendered version of a document, so that document order or structure may be lost (e.g., when tables are used for layout) and their output may be confusing.

Speech (or voice) recognition is used by people with some physical disabilities or temporary injuries to hands and forearms as an input method in some voice browsers. Applications that have full keyboard support can be used with speech recognition.

Speech synthesis or speech output can be generated by screen readers or voice browsers, and involves production of digitized speech from text. People who are used to using speech output sometimes listen to it at very rapid speeds.

Some accessibility solutions are adaptive strategies rather than specific assistive technologies such as software or hardware. For instance, for people who cannot use a mouse, one strategy for rapidly scanning through links, headers, list items, or other structural items on a Web page is to use the tab key to go through the items in sequence. People who are using screen readers -- whether because they are blind or dyslexic -- may tab through items on a page, as well as people using voice recognition.

Text browsers such as Lynx are an alternative to graphical user interface browsers. They can be used with screen readers for people who are blind. They are also used by many people who have low bandwidth connections and do not want to wait for images to download.

Visual notification is an alternative feature of some operating systems that allows deaf or hard of hearing users to receive a visual alert of a warning or error message that might otherwise be issued by sound.

@@ update WCAG 1.0 to WCAG 2.0
@@ drop the curricular refs?
@@ possibly link to relevent section of "Understanding WCAG 2.0" for clarification at second-level bullet rather than "www.w3.org/WAI/wcag-curric/" or in some circumstance it may be better to link to specific techniques (eg H43 for complex tables).

This section is not a comprehensive listing of accessibility provisions in the three sets of guidelines.

UAAG 1.0 Checkpoint 4.3 (Priority 1) Allow the user to configure the foreground color of all text, with an option to override author-specified, and user agent default, foreground colors. Allow the user to select from among the range of system colors.

UAAG 1.0 Checkpoint 4.4 (Priority 1) Allow the user to configure the background color of all text, with an option to override author-specified and user agent default background colors. Allow the user to select from among the range of system colors.

WCAG 1.0 Checkpoint 1.3 (Priority 1) Until user agents can automatically read aloud the text equivalent of a visual track, provide an auditory description of the important information of the visual track of a multimedia presentation.

{ WCAG 1.0 Checkpoint 4.2 (Priority 3) Specify the expansion of each abbreviation or acronym in a document where it first occurs. For example, in HTML, use the "title" attribute of the ABBR and ACRONYM elements. Providing the expansion in the main body of the document also helps document usability.

UAAG 1.0 Checkpoint 4.5 (Priority 1) Allow the user to slow the presentation rate of audio, video and animations that are not recognized as style. For a visual track, provide at least one setting between 40% and 60% of the original speed. For a prerecorded audio track including audio-only presentations, provide at least one setting between 75% - 80% of the original speed. When the user agent allows the user to slow the visual track of a synchronized multimedia presentation to between 100% and 80% of its original speed, synchronize the visual and audio tracks. Below 80%, the user agent is not required to render the audio track.

{ WCAG 1.0 Checkpoint 10.1 (Priority 2) Until user agents allow users to turn off spawned windows, do not cause pop-ups or other windows to appear and do not change the current window without informing the user.

The World Wide Web is full of information about disabilities. The key can be locating information that is relevant to the issue of accessibility to the Web, and is accurate and up-to-date. It can be important to note the perspective from which the information is written. For example, there is much information about different diseases on the Web, but medical details can be less relevant to understanding how people with disabilities use the Web than the perspectives of people with disabilities themselves; information about assistive technologies used with the Web; and information from organizations that focus on accessibility strategies for using information technologies and telecommunications. One way to start is by doing Web searches on the terms used in this document.

Coordinate with research and development efforts that may affect accessibility of the Web

WAI's International Program Office enables partnering of industry, disability organizations, accessibility research organizations, and governments interested in creating an accessible Web. WAI sponsors include the US Department of Education's National Institute on Disability and Rehabilitation Research; the European Commission's Information Society Technologies Programme; Government of Canada, Industry Canada; Fundacion ONCE, HP, IBM, Microsoft Corporation, SAP, Verizon Foundation, and Wells Fargo. Additional information on WAI is available at http://www.w3.org/WAI/.

The W3C was created to lead the Web to its full potential by developing common protocols that promote its evolution and ensure its interoperability. It is an international industry consortium jointly run by the Computer Science and Artificial Intelligence Laboratory (CSAIL) at Massachusetts Institute of Technology (MIT) in the USA, the [European Research Consortium for Informatics and Mathematics (ERCIM) in France]{National Institute for Research in Computer Science and Control (INRIA) in France} and Keio University in Japan. Services provided by the Consortium include: a repository of information about the World Wide Web for developers and users; reference code implementations to embody and promote standards; and various prototype and sample applications to demonstrate use of new technology. For more information about W3C, see http://www.w3.org/.